Motorola appears to have set back its schedule for the release of the PowerPC G4 Plus in volume quantities - ie. sufficient for Apple to begin shipping Macs based on the chip in earnest.

According to Motorola sources cited by AppleInsider, the chip maker has pushed the G4 Plus back to June.

The next-generation G4 CPU is believed to have been completed late last summer. But taping out a chip and shipping it in volume are two very different matters. Motorola will have spent the intervening months refining its design and its production process, eliminating bugs in both.

We reckoned the G4 Plus won't appear in Macs until later this quarter at the very earliest - and given Motorola's record to date on shipping G4s, that timeframe could easily slip, as AppleInsider's sources are now suggesting. Indeed, around the time the G4 Plus taped out, Motorola sources reckoned the company's schedule would allow Apple to ship Macs based on the chip by "mid-summer".

Motorola understandably applies fairly broad deadlines to its chip shipment schedule, and the slide to June falls well within what we've been led to expect.

The G4 Plus is central to Motorola's programme to accelerate the chip to 1GHz and beyond. Though the chip is expected to debut at around 750MHz, it is designed to be quickly clocked up to much higher speeds - something Apple is desperate to achieve.

According to AppleInsider's sources, Apple is hoping that overclocked PowerPC 7410s - the latest, .18 micron version of the original G4, the PowerPC 7400, aimed at the embedded market - will close some of the gap between its current maximum speed of 500MHz and the Wintel world's 1GHz and up.

Faster Power Mac G4s are expected to debut at MacWorld Expo in San Francisco next week. As evidence, some sites suggest Apple's latest price cuts, though these are as much about hacking back the company's inflated product inventories as paving the way for the new machines. ®